[PATCH v3] pwm: sun4i: fix a possible NULL dereference

From: LABBE Corentin
Date: Wed Aug 24 2016 - 08:00:43 EST


of_match_device could return NULL, and so cause a NULL pointer
dereference later.

For fixing this problem, we use of_device_get_match_data(), this will
simplify the code a little by using a standard function for
getting the match data.

Testing the return value of of_device_get_match_data is also necessary
for avoiding a second NULL deref on pwm->data.

Reported-by: coverity (CID 1324139)
Signed-off-by: LABBE Corentin <clabbe.montjoie@xxxxxxxxx>
---
Changes since v2:
- Add a test on pwm->data for avoiding a second NULL deref.
Changes since v1:
- Use of_device_get_match_data()

drivers/pwm/pwm-sun4i.c | 7 +++----
1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/drivers/pwm/pwm-sun4i.c b/drivers/pwm/pwm-sun4i.c
index 03a99a5..fb76c55 100644
--- a/drivers/pwm/pwm-sun4i.c
+++ b/drivers/pwm/pwm-sun4i.c
@@ -309,9 +309,6 @@ static int sun4i_pwm_probe(struct platform_device *pdev)
struct resource *res;
u32 val;
int i, ret;
- const struct of_device_id *match;
-
- match = of_match_device(sun4i_pwm_dt_ids, &pdev->dev);

pwm = devm_kzalloc(&pdev->dev, sizeof(*pwm), GFP_KERNEL);
if (!pwm)
@@ -326,7 +323,9 @@ static int sun4i_pwm_probe(struct platform_device *pdev)
if (IS_ERR(pwm->clk))
return PTR_ERR(pwm->clk);

- pwm->data = match->data;
+ pwm->data = of_device_get_match_data(&pdev->dev);
+ if (!pwm->data)
+ return -EINVAL;
pwm->chip.dev = &pdev->dev;
pwm->chip.ops = &sun4i_pwm_ops;
pwm->chip.base = -1;
--
2.7.3